Amazon.com is planning to launch a free, advertising-supported video service for the estimated 48 million people who use its Fire TV streaming video devices, say people familiar with the situation. The new service, which is being developed by Amazon’s IMDB subsidiary, will join a growing collection of efforts by Amazon to tap into the $70 billion TV ad market.

The company has already introduced ad-supported shows on IMDB, expanded video ads on its gaming site Twitch and run ads on NFL games on Prime Video, its primary streaming service. It is also expected to run ads on Prime Video in Europe for some sports events, said one of the people.